1. Field of the Invention
The present invention relates to an image forming apparatus, such as an MFP (Multi-Function Peripherals) as a digital compound machine, a copier or a printer, and a toner cartridge used for the image forming apparatus.
2. Description of the Related Art
Heretofore, an image forming apparatus such as an MFP includes a toner cartridge for supplying toner to a developing device. The toner cartridge is attachable/detachable to/from the image forming apparatus, and when the toner in the toner cartridge runs out, the user can replace the toner cartridge.
In a conventional image forming apparatus, in order to prevent a toner cartridge not meeting the specifications from being mounted, there is an example in which a storage medium, such as a nonvolatile memory or an IC tag, is attached to a main body of the toner cartridge, and data such as a model number is stored in this storage medium. In the image forming apparatus, the data of the model number stored in the storage medium is read to judge whether the toner cartridge meets the specifications, and it is prevented for an incorrect toner cartridge from being mounted.
Besides, in addition to the data of the model number of the toner cartridge, data such as the date of manufacture and a toner capacity are also stored in the storage medium, and the image forming apparatus reads the data of the toner capacity to calculate data of toner empty, or reads the data of the date of manufacture to limit the use of the expired toner. Besides, in addition to the method of storing various data in the storage medium, there is also a method in which a bar code label is affixed to a main body of a toner cartridge, and the bar code is read by a reader to obtain various information.
JP-A-5-224479 discloses an example in which a bar code is displayed on a toner cartridge and a bar code reader is provided in an image forming apparatus. In this example, the bar code displayed on the toner cartridge is read by the bar code reader, so that it is judged whether or not the proper toner cartridge is mounted.
However, in the example in which the bar code reader is used, the bar code reader is expensive. Then, although it is also possible to read the bar code displayed on the toner cartridge by an inexpensive photosensor or the like, there is a defect that in the case where the toner cartridge is manually mounted, since the insertion speed at the time of mounting is changed, the bar code can not be accurately read by the photosensor.
Besides, JP-A-11-194599 discloses an example in which a display body capable of displaying a temperature history is affixed to a toner cartridge. In this example, when the toner cartridge is placed in a high temperature atmosphere for a long time and the toner is deteriorated, the deterioration can be detected. The display body changes its color when it is left in the high temperature for a long time, and the change of the color of the display body is read by a sensor provided in an image forming apparatus.
In the example using the display body to display the temperature history, it is necessary to use the special display body whose color is changed by the temperature change. Besides, there is a defect that other various information can not be stored in the display body.
The invention provides a toner cartridge in which information intrinsic to the toner cartridge can be easily read by a photosensor or a mechanical switch, and an image forming apparatus.